BRCA1/2 mutations and FMR1 alleles are randomly distributed: a case control study

Area of Science:

• Genetics
• Reproductive Biology
• Cancer Genetics

Background:

• Previous studies suggested a link between BRCA1/2 mutations and specific Fragile X Mental Retardation 1 (FMR1) genotypes.
• This association was interpreted as a mechanism to prevent embryo-lethality in BRCA1/2 mutation carriers, mediated by low FMR1 alleles.

Purpose of the Study:

• To re-evaluate the distribution of FMR1 genotypes in Ashkenazi women carrying BRCA1/2 founder mutations.
• To determine if an association exists between FMR1 low genotypes and BRCA1/2 mutations in a homogeneous ethnic cohort.

Main Methods:

• Genotyping of FMR1 alleles (categorized as low, normal, and high CGG repeat numbers) was performed.
• A cohort of 125 Ashkenazi BRCA1/2 mutation carriers was analyzed.
• A control group of 368 Ashkenazi healthy females was included for comparison.

Main Results:

• Both BRCA1/2 carriers and control groups exhibited comparable and non-skewed distributions of FMR1 subgenotypes.
• No significant association was found between FMR1 low genotypes and the presence of BRCA1/2 mutations in this cohort.

Conclusions:

• The study did not confirm the previously reported association between FMR1 low genotypes and BRCA1/2 mutations.
• The hypothesis that BRCA1/2 mutations are embryo-lethal without rescue by low FMR1 alleles is refuted based on these findings.